In the second period of a regular season game against the Toronto Maple Leafs on March 2, 2007, Janssen knocked Toronto defenseman Tomas Kaberleunconscious with a late hit to the head. Kaberle was carried off the ice on a stretcher.[3] The NHL announced Janssen would be suspended for three games without pay for the incident, forfeiting $7,220.16.[4] In an interview, Kaberle mentioned that Janssen had not contacted him for reconciliation, and went on to say, "I don't care [to hear from him]. He doesn't respect me and I don't respect him."[5]

A free agent after his contract with the St. Louis Blues expired in 2011, Janssen signed a one-year, two-way contract with the Devils on July 14, 2011[8] becoming the 22nd player to be re-acquired and play for the team.[9]

Janssen signed as a free agent on a one-year contract with the Nottingham Panthers of the EIHL on August 15, 2015.[10]

In July 2012, Janssen appeared on an internet-based radio show called "The Thom and Jeff Show" and subsequently delivered a profanity-laced interview in which he made several controversial comments, including one about gay players. Janssen later issued an apology for the incident, noting that he had "used poor judgment during the course of the show" and saying "moving forward, I hope to eliminate that type of language from my vocabulary. I would also like to take this chance to express my support for the work the You Can Play project is doing, and for the gay community in general."[11][12]